Due to architectural differences, AMD CPUs are immune or nearly immune to some of the speculative execution attacks (though not all of them). For example, AMDs branch predictor uses the full address and so is not vulnerable to branch predictor poisoning in the same way as Intel.

The major win (whether AMD intended it or not) is that AMD cpus don't speculate loads until page permissions have been verified. Intel fires off the speculation immediately. That is one of the primary side channels underlying many of the attacks.

Intel has been actively muddying the waters with FUD to get people to think AMD is just as vulnerable. Please don’t buy into that. Intel is far more exposed. The subsequent slowdowns are more severe.